Silver halide emulsions for black and white prints containing brightening agents



United States Patent lice SILVER HALIDE EMULSIONS FOR BLACK AND WHITE PRINTS CONTAINING BRIGHTENING AGENTS William H. Libby and Harlan B. Freyermuth, Easton, Pa., assignors to General Aniline & FilmCorporation, New 1 York, N. Y., a corporation of Delaware No Drawing. Application March 23, 1951, Serial No. 217,306

6 Claims. (Cl. 95-7) The present invention relates to photographic emulsions and particularly to sliver halide emulsions for black and white prints containing a condensation product of 4,S-diphenylglyoxalonedisulfonyl chloride with an organic amine as a brightener of the white portions of the silver image formed after exposure and development of said emulsion.

The white portions in most black and white photographic prints regardless of the nature and constitution of the base material possess a grayish or yellowish cast or tint. This cast is more pronounced after the print has been stored for some time, even in the absence of natural or artificial light. The cast or tintis probably due to the degradation products of the photographic developer formed during development of the silver image.

It is known that many organic compounds known as 2,723,197 Patented Nov. 8, 1 955 2 a The compounds characterized by the foregoing general formula are readily prepared by condensing one molecular proportion of 4,5-diphenylglyoxalonedisulfonyl chloride with at least two molecular proportions of a primary or secondary aliphatic, aromatic, or heterocyclic amine, containing an alkyl chain of at least six carbon atoms and a solubilizing group, such as sulfonic or carboxylic acid.

The 4,5-diphenylglyoxalone'disulfonyl chloride is dissolved in a sufficient volume of anhydrous pyridine and added to a mixture of the amine which is also dissolved in anhydrous pyridine and to the mixture a small quantity of anhydrous sodium ac'eate is added, and the mixture heated at the temperature of steam for about five to seven hours. After cooling, the solid product is isolated by recrystallization from hot water.

The unusual feature of the foregoing condensation reaction is that any primary or secondary aliphatic, aromait is essential that the amine, whether primary or second:

tic, or heterocyclic amine will condense with the 4,5-diphenylglyoxalonedisulfonyl chloride under the aforestated conditions to produce compounds corresponding to the above formula. However, for purposes of this inventiop,

ary, aliphatic, aromatic, or heterocyclic, contain as a substituent both an alkyl chain of at least six carbon atoms and a water solubilizing group, such as carboxylic or sulfonic acid. The inclusion. of the alkyl chain of at least six carbon atoms imparts non-diffusing properties brightening agents are utilized for the treatment of textiles to impart an overall whitening in bright light. Brightening agents of the stilbene type are currently utilized for this purpose and afiect textiles uniformly causing a whitening of each portion thereof. Cellulosic derivatives usually have a yellowish tint and in order to counteract the undesirable tint, brightening agents, particularly spirit-soluble safranine, are incorporated into the cellulosic derivative or in a bonding layer which is coated over the derivative or between two sheets of the cellulosic derivative. 1

Inasmuch as practically all of the brightening agents cause the fabrics and cellulosic derivatives to which they are applied to assume an overall whiteness, considerable difficulty ws encountered in solving the foregoing photographic problem. Most of the currently used brightening agents when applied to photographic images pro'duce not only a brightening of the white areas but also a whitening of the shadowy dark areas. Similarly, it applied to color film, the brightening agents not only affect the white portions of the images, but the colored portions as well. We have discovered that a certain class of'brightening agents, when incorporated into silver halide emulsions for producing black and white images upon exposure and developement of the silver halide, operate very noticeably on the white portions of the black and white images, thus causing a noticeable increase in contrast. Such compounds are products obtained by the condensation. of l,5-diphenylglyoxalonedisulfonyl chloride withan organic nnine and are characterized by the following general formula: 1

to the compound and the water solubilizing group permits moderate solubility in water for incorporation into silver halide emulsions.

The various amines which maybe condensed with 4,5-diphenylglyoxalonedisulfonyl chloride are legion and no difficulty will be encountered in selecting the proper one so as to yield the desired product. As illustrative examples of such amines, the following may be mentioned:

AROMATIC 1 amino 4 methyloctadecyl aminobenzene-Il-sulfonic acid.

1-amino-4-dodecylaminobenzene-ll-carboxylic acid.

1 amino 4 perhydrodiphenylaminobenzene-3-carboxylic acid.

1-amino-2-oleylaminobenzene-S-sulfonic acid.

1 amino 2 methyloctadecylarninobenzene-3-carboxylic acid.

1-amino-2-dodecylaminobenzene-3 sulfonic acid. 6-tetradecylamino metanilicacid.

6-cetylarnino metanilic acid.

6-octadecylamino metanilic acid. 6-myristoylamino-2-toluidine-4-sulfonic acid. 6-palmitoylamino-2-toluidine-4-sulfonic acid. 6-stearoylamino-Z-toluidine-4-sulfonic acid. 6-(N-methyl-N-tetradecanoylamino) -metanilic acid. 6-(N-methyl-N-octadecanoylamino) -metani1ic acid. 6-(N-ethyl-N-tetradecanoylamino)-metanilic acid.

. 6-(N-ethyl-N-cetanoylamino)-metanilic acid.

6-(N-ethyl-N-octadecanoylamino) -metanilic acid.

HETEROCYCLIC l-tetradecyl-Z-(4-aminophenyl)-benzimidazole-5-sulfonic acid. 1-cetyl-2-(4-aminophenyl)-benzimidazole-5-sulforuc acid. l-octadeeyl-Z-(4-aminophenyl)-benzimidazole S-sulfonic acid. 1

. v ALIPHATIC N-tetradecyl taurine. N-cetyl taurine. N-octadecyl taurine. N-tetradecyl glycine: N-cetyl glycine.

N-octadecyl glycine.

3 It is .to be clearly understood that the configuration or structure of the aliphatic, aromatic, and heterocyclic amine, whether primary or secondary, is immaterial so long as :itcontains an alkyl substituent in any part of the molecule of at least six carbon atoms and a water solubilizing group. These amines may be further characterized by the following formulae:

ALIPHATIC a HN-CHzCHzSOsH and 1?: HNG-H:C'O OH AROMATIC sour and S O a HETEROCYCLIC German Patent 165,126

and

ENOG

wherein R2 represents hydrogen or a lower alky., such as methyl, ethyl, propyl, 'butyl, -etc., and R3 represents an alkyl chain of at least six carbon atoms, .such as hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tridecyl, tetradecyl, pentadccyl, heptadecyl cetyl, octadecyl, and the like.

The brightening compounds characterized by the above general formula are incorporated into any type of-s'ilver halide emulsion employed in the manufacture of photographic contact and projection paper.

In the preparation of silver halide emulsion whether a single silver halide salt or a mixture of silver halides, such as chlorobromides, bromoiodides, or chlorobromoiodides, the brightening agents per se in finely divided form. or a solution thereof in water or an alcohol-water mixture is made and the powdery form or a solution thereof is mixed with the emulsion at any point during its preparation, i. e., ripening, curing, or settling stage, but preferably during ripening or just prior to coating. The concentration of the brightening agent incorporated into the silver halide emulsion may be any amount which will brighten the white portions of the print after exposure and development of the emulsion. Brightening amounts may 4 range from about 0.05 to 10 grams per liter of emulsion to yield satisfactory results. The amount added is not critical and perceptible results are obtained with quantities below 50 milligrams per liter of any type of emulsion. Increasing the amount beyond 10 grams per liter serves no useful purpose and may have a yellowing effect.

The actual concentration employed will depend upon the type of emulsion 'used and varies slightly with the brightening agent employed, and the brightening amount to be actually employed can be very readily determined by simple routine tests. In case a water or alcohol-water solution is employed, it is best prepared by dissolving the brightening agentin the smallest amount of solvent necessary to effect solution and the solution added with stirring to a silver halide emulsion so that the final volume of the silver halide emulsion will be one liter.

When applied within the stated proportions to silver halide emulsions, the white portions of the prints after exposure and development are considerably whiter with aconsiderable increase in the contrast when compared to a .control black and white print. When applied to color prints, very little brightening is observed. In fact, a tonal change may be brought out in the blue and magenta layers. The unusual feature of the brightening agents utilized in accordance with the present invention is that since they are substantive to photographic colloids, such as gelatin, polyvinyl alcohol, and the various gelatin substitutes, they are not readily removed during the development and washing steps of the exposed print and are retained in the colloid layer indefinitely and enhance the brightness of the white areas of the photographic images.

The colloidal carrier for the silver halide emulsion may be gelatin, water soluble cellulose derivatives, such as hydroxylethylcellulose, methylcellulose, carboxyrnethylcellulose, low acetyl value cellulose, polyvinyl alcohol, partially hydrolyzed polyvinyl acetate, acetals of polyvinyl alcohol, partially hydrolyzed vinyl acetate-ethylene copolymers, and the like. A surface active agent, such as sulfated oleic acid, alkylated monosodium benzenesul fonate, dihexyl ester of sodium sulfosuccinate, sodium salt of an alkylnaphthalene sulfonic acid, sodium salt of tetrahydronaphthalene sulfonic acid, calcium glycerin phosphate, alkylphenyl-polyethylene glycol, oleic acid ester of hydroxyethane sulfonic acid, and sulfonates of high molecular weight primary or secondary aliphatic, aromatic, and cycloalipahtic carboxy acids, may be added to effect a smoother coating. It is to be noted, however, that any commercially available surface active agent may be employed. The nature of the surface active agent is immaterial'so long as it possesses wetting, dispersing, and emulsifying properties, and its aqueous solutions are colorless or only slightly tinted.

The black and white photographic material may be either a contact printing paper, a projection printing paper, ordinary black and white film, which may be a positive or negative, or motion picture film. The addition products whether incorporated in the silver halide emulsion layer or as a supercoating over the emulsion layer aresubstantive to gelatin and other water permeable colloids, and as a consequence, non-diffusing in photographic processing baths.

The base material, i. e., support for the silver halide emulsion may be the usual baryta paper, white opaque cellulose acetate, and the like. In fact, the nature or constitution of the base is immaterial since the effect is in the white portions-of the silver image. I

Another unusual feature-of the brightening agents utilized in accordance with the present invention is that they may also be employed in the pigmenting layer of a photographic paper or white opaque cellulose acetate to enhance the brightness of the White areas of the photographic image in the overcoated colloid layer. The photographic paperor white opaque cellulose acetate is coated with a layer of pigment, such as barium. sulfate,

titanium dioxide, calcium carbonate, calcium sulfate, color, i; e.,, ,cast or tint, of the silverimage the picture feldspar, fluorspar, neutral calcium phosphate, and the area in the two emulsions is then observed and found like, dispersed in the same colloid carrier which is utiin all cases to be less in the emulsions containing brightenlized for carrying the silverhalide emulsion as described ers. above. The percentage of the pigmenting agent may be The invention is further illustrated by the following that ordinarily employed in the case of gelatin baryta examples, but it is to be understood that the inventionv coatings and is well known in the art. In this applicais not limited thereto. All the parts are given as parts tion, the brightening agents are employed in a concentraby weight unless, otherwise specified.

Example I I CH3 CH3 1 Q 011E350 ONH NHOS m r 1 in SO3NH NHCOC11H \i/ 0111 QaH tion ranging from 0.1 gram to 15 grams per liter of a A mixture of 108. parts of 4,S diphenylglyoxalonedisulwater dispersion of the colloid carrier and pigm'enting,v fonyl chloride in I300 parts of anhydrous pyridinewas agent. The dispersion is spread upon the paper or white added tov a mixture of 352 parts of 6-stearoylamino-2- opaque cellulose acetate in a thin coating. Upon evapotoluidine-4-sulfonic acid in 1700 parts of anhydrous ration of the water, a pigmented colloid layer is obtained. pyridine. 41 parts of anhydrous sodium acetate were The light sensitive photographic paper'or white opaque added and the mixture heated at the temperature of cellulose acetate is then formed by applying asilver halide steam for six hours; After cooling, the solid product was photographic emulsion layer to the pigmented layer in isolated inthe usual manner by' recrystalliaztion from hot the usual manner. water;

' .Examplei-II t t-ck r 4 N" HNO:S HN\ H, SOzNH N 1 i H 0/ Boss \N -.SO2EI Despite the fact that the brightening agents are mod- The procedure of Example I was repeated with the erately soluble in water, they do not, however, form any exceptionfithat' 335 parts of l-tetradecyl-2-(4-aminophenquantitative amount of insoluble salts when in contact yl)-benzimidazole-5-sulfonic acid were used in place of with any one of the pigmenting agents. The very small 352 parts of '6-stearoylamino-2-toluidine-4-sulfonic'-acid.

Example'lll amount of water insoluble salt that may be formedwill The procedureof Example I was repeated with the not affect the brightening agents substantivity to the colexception that 406 parts of 1-octadecyl-2-(4-aminophenloid carrier. yl)-benzimidazole-5-sulfonic acid were used in place of The method of testing the etfect in silver halide emul 352- parts of 6-stearoylamino-Z-toluidine-4-sulfonie acid.

' v Example IV Nois f 1mg /NH SO1N Ho semen, CHrCHzSOzB' sions consists merely of coating a film or paper support .The procedure of Example I was repeated with the with the same emulsion, one with and one without the exception that 283 parts of N-octadecyl taurine were brightening agent,- exposing and developing the film or used in place of 352 parts of 6-stearoylamino-2-toluipaper, and then storing it for a period of three to six dine-4-sulfonic acid. I

Example V 0H3. on;

' HN H SO1NH ---NH0 0 011B" 03H months either in a closed container or in a photograph The procedure of Example I was again repeated with album thatis exposed to the atmosphere. The change in the exception that 309 parts of 6-myristoylamino-2- 2,723,197 3 tolui'dine-4-sulfonic acid were used in place of 352parts grams of the product o'f'Example 'I were replaced by l of 6 stearoylaminoQ-tdluidine 4-slilfoni'c acid. gram of the product or Example V. U on -"exposure and Example VI development, the white portion "of the print "was considerably Whiter, the contrast was noticeably increased To a gelatin silver chlorobromide emulsion of normal h compared with a "control black and white p'ri'n't,

Speed and Contrast, grams Pmdlmt Example and thewhitening agent employed showed no deleterious I dissolved in 250 cc. of hot water'were addedwith stirff t upon th fi i hed photographic print,

ring and the p to 0116 Silver halide emulsions containing the brightening After the brightening agent was thoroughly dispersed in agents of the present invention have the added advanthe Cmulsiofl, the emulsion Was coated P a Subbed 10 rage in that the agents do not influence the speed of the p p r base, allowed to y, and thou xp and contrast of the unexposed emulsion while in package Veloped to a Silver image- "Another P p base form and storage. The brightening agents may be used W h h Same emulsion but containing 110 brightening on various kinds of silver halide emulsions. In addition agent was xp and developed to a Silver g to being useful in silver chloride emulsions, they may be Both prints were placed p a laboratory shelf and usedin chloride, bromide, bromoiodide, and chloroexamined after several weeks. The print containing the b oiodid emul io s. They are equally useful in brightening agent Showed remarkable iIIlPYQVemeIlt ill sensitized and unsensitized emulsions, boil type, ammonia brightness, i. 'e., the white portions were definitely a type, and paper emulsions of various types.

bright white color, whereas t print h h contained Various modifications of this invention will "occur to n brightening agent Showed Considerable y wi h those skilled in the art and it is, therefore, understood cast. that the invention is limited only by the scope of the Example VII appended claims.

Example 'VI was repeated with the exception that 6 I y A grams of the product of Example I were replaced by 8 A h Y P P 5 F5 9 i i grams of the product of Example II. Upon exposure bIaFk and W i Images i P 5? P P and development the white portion of the print was com a llghtsensit ve silver halide emulsion layer containing, siderably whiter, the contrast was noticeably increased bnghteflmg m bnghtemn? capable of when compared with a control black and white print, bnghtemng the Whlte pol-Hons of the .Sllver miage formed and the Whitening agent employed showed no deleterious exposure and Y of Sald emulslon charac' efiect upon the finished photographic print terized by the followmg general formula:

Example VIII R @o=c R Example VI was repeated with the exception that NSOz Hl l 1 m SO2N/ 6 grams of the product of Example I were released by R1 0 R1 2 grams of the product of Example III. Upon exposure II and development, the white portion of the print was 0 considerably whiter, the contrast was noticeably inwherein R represents a member selected from the class creased when compared with a control black and white consisting of hydrogen, aliphatic, aromatic, and heteroprint, and the whitening agent employed showed no cyclic radicals, R1 represents an aliphatic, aromatic, or

deleterious eifect upon the finished photographic print. heterocyclic radical, one of said radicals consisting of R and R1 containing an alkyl group of at least six carbon Example IX atoms and a water 'solubilizing group selected from the Example VI was repeated with the exception that class consisting of carboxylic and sulfonic. 6 grams of the product of Example I were replaced by 2. A photographic material according to claim 1, 0.5 gram of the product of Example IV. Upon expowherein the brightening agent is characterized by the sure and development, the white portion of theprint following formula;

CH3 CH3 Q: t= t-C 011E ONE. NHO:S H'N NH sorNr't -NHC 0 ohm, \E/

' 0:11 03H was considerably whiter, the contrast was noticeably increased -when compared with a control black and White 3. A photographic material according to claim 1, print, and the whitening agent employed showed no delewherein the brightening agent is characterized by the terious effect upon the finished photographic print. following formula:

, 4. A photographic material according to claim 1, that 6 wherein the brightening agent is characterized by the n following formula:

1 1 nNms HN NH sorNn N C e V i .nors I v I sod;

Example X Example VI was repeated with the "exception 2,723,197 9 10 5. A photographic material according to claim 1, wherein the brightening agent is characterized by the following formula:

6. A photographic material according to claim 1, wherein the brightening agent is characterized by the following formula:

H27C174COHN -HNO:S EN SOzNH NHOCCnHzI SOzH 803R References Cited in the file of this patent UNITED STATES PATENTS 2,186,849 Wilmanns et al Jan. 9, 1940 2,317,184 Dreyfuss Apr. 20, 1943 FOREIGN PATENTS 878,823 France Nov. 2, 1942 498,125 Belgium Sept. 30, 1950 672,803 Great Britain May 28, 1952 OTHER REFERENCES Melliand: Textilberichte, October 1949, p. 488. Rayon and Synthetic Textiles, October 1948, pp. 89 and 90. 

1. A LIGHT SENSITIVE PHOTOGRAPHIC EMULSION FOR FORMING BLACK AND WHITE IMAGES THEREIN COMPRISING A SUPPORT AND A LIGHT SENSITIVE SILVER HALIDE EMULSION LAYER CONTAINING, IN A BRIGHTENING AMOUNT, A BRIGHTENING AGENT CAPABLE OF BRIGHTENING THE WHITE PORTIONS OF THE SILVER IMAGE FORMED AFTER EXPOSURE AND DEVELOPMENT OF SAID EMULSION, CHARACTERIZED BY THE FOLLOWING GENERAL FORMULD: 